1. Field
Exemplary embodiments of the present invention relate to an integrated circuit chip, and more particularly, to buffers for receiving signals inputted to an integrated circuit chip and drivers for outputting signals to an outside of the integrated circuit chip.
2. Description of the Related Art
Various integrated circuit chips operate while transmitting and receiving data (signals) to and from other chips. For example, memory chips such as a DRAM and a flash memory transmit and receive data to and from memory controllers. Also, a CPU transmits and receives data to and from various chips on a mother board. With the development of technologies, a data transmission speed is increased. As a data transmission frequency is increased, a data eye for data recognition is decreased. The decreased data eye may be more vulnerable to influences from power noise or impedance mismatching caused due to internal or external factors of a chip and influences by variations in processes.
Data transmission types are divided into a single ended type and a different type. Single ended type data transmission refers to a type in which one data is transmitted to one data pad, and it may be vulnerable to noise, while having the large number of channels and reduced current consumption. Differential type data transmission refers to a type in which one data is transmitted to two data pads in such a manner that main data is transmitted to one data pad and sub data (data obtained by inverting the main data) is transmitted to the other data pad. In such differential type data transmission, the logic value of data is recognized by comparing the voltage levels of the main data and the sub data. Therefore, the differential type data transmission has the small number of channels and augmented current consumption, while being invulnerable to noise.
Thus, a technique for appropriately combining the single ended type data transmission and reception and the differential type data transmission and reception is being developed.